The high-throughput filling of containers with liquids is accomplished using precision, automated liquid filling systems. These high speed liquid filling systems are used for filling containers such as bottles, cans and jars with a wide variety of consumer products including foods, drinks, personal care products, home care products, automotive products, pharmaceuticals and more.
A typical liquid filling system includes a container handling device, a liquid filling machine and a capping/lidding machine. The container handling device transports unfilled containers to the liquid filling machine and then transports the filled containers from the filling machine to the capping/lidding machine. The container handling device commonly comprises one or more conveyors and may also include one or more indexing devices such as gates, star wheels or spindles. The liquid filling machine comprises a plurality of filling stations such that it can simultaneously fill multiple containers. Each filling station includes a nozzle and a valve connected to a source of liquid product such as a tank or reservoir. The nozzles direct liquid product into the container. The nozzle may be configured to physically engage the opening in the container, to be placed through the opening and into the interior of the container, or simply to be placed in the vicinity of the opening in the container. The liquid product may be pumped to the nozzles of each filling station using a pump such as a positive displacement pump, by a source of pressure such as compressed air, or simply by gravity feed. The nozzle and valve may be separate components or they may be integrated into a single device. The valve is opened and closed to control the flow of liquid product that flows through the nozzle and into the container. In order to minimize foaming and splashing of product during the filling process, each filling station may include a bottom-up fill mechanism which places the nozzle tip in the vicinity of the bottom of the container at the initiation of the filling process and then withdraws the nozzle as the container is filled and the product level rises. The relative movement of the nozzle and the container may be accomplished by lowering and raising the nozzle, the container or both. The system may also include a labeling machine and a packing station for packing a plurality of filled containers into cartons or boxes for shipping.
Liquid filling machines are generally of two types, rotary filling machines and in-line filling machines. Because it easily allows for fast, continuous motion of containers, rotary filling machines are the fastest known architecture. Turning to FIG. 1, a typical rotary filling machine 10 is shown. The rotary filling machine 10 comprises a plurality of filling stations 12, arranged around the circumference of a revolving rotor 14 which rotates in the direction shown by arrow 11. Each filling station 12 includes a filling device 16 typically having a nozzle 18 and a container holding device (not shown) for securely holding and aligning each container as the containers rotate with the rotor 14 during the filling process. Each nozzle 18 is connected to a hose 20. The other end of the hose 20 is connected to a product reservoir (not shown). A conveyor 22 transfers empty containers to an input spindle 13 which synchronously feeds the each successive empty container to a filling station 12. As each container travels around the filling zone with the rotor 14, the container is filled with product by the filling device 16. Once the container is filled, it has rotated to an output spindle 23 which removes the container from the filling station 12 and feeds the filled container back to the conveyor 12. Another section of the conveyor 22 may then transport the filled containers to a capping/lidding machine (not shown), labeling machine (not shown) and/or a packing station (not shown). Several rotary filling machines are described in U.S. Pat. No. 6,761,191 and U.S. Pat. No. 6,474,368, the disclosures of which are hereby incorporated by reference herein in their entireties.
In-line filling systems are characterized by the motion of the containers in a generally straight line through the product filling area. There are many types of in-line filling systems but they can be broken down into two types of motion, namely intermittent motion and continuous motion. In the intermittent motion designs, a group of empty containers are serially conveyed or indexed into a plurality of filling stations. The containers are then completely filled while they remain fixed and motionless. Once this group of container is filled, an indexing mechanism transports the filled group of containers out of the filling area and another group of empty containers are conveyed into the position of the filling stations. In order to increase the throughput of this type of in-line filling system, various derivative designs have been devised to increase the throughput. These include the multiple parallel lane and nozzle design, the dead plate pushover design, the shifting nozzle design, and the parallel lane/staggered nozzle design.
Each of these designs is described in detail in U.S. Pat. No. 5,878,796, the disclosure of which is hereby incorporated by reference herein in its entirety.
It is also possible to have an in-line filling system which provides for continuous motion of the containers. One such design is the walking beam design, an example of which is shown in FIG. 2. The walking beam filling system 30 comprises a conveyor 32 which transports containers 34 to and from the liquid filling zone 36. The containers 34 move continuously in a straight line along the conveyor 32. A bank of nozzles 38 is mounted to a beam 40. The nozzles 38 are spaced apart such that each nozzle will align with the opening of the same number of containers 34 as the containers 34 travel through the filling zone 36. The beam 40 is affixed to a motorized beam mechanism 42 which moves the bank of nozzles 38 laterally back and forth along the same line as the containers 34 on the conveyor 32. The motorized beam mechanism 42 moves the beam 40 and the bank of nozzles 38 in the direction 44 synchronously with the movement of a group of containers 34 as the containers 34 are filled by the nozzles 38. The motorized beam mechanism 42 then returns the beam 40 and nozzles 38 back in the direction 46 at a rate of speed substantially greater than the speed of the conveyor 32. A filling cycle begins when the beam 40 is accelerated from rest at an initiation point to match the speed of the movement of the continuously moving containers 34 on the conveyor 32 and the nozzles 38 are positioned over the openings in the containers 32. The nozzles 38 are then lowered into the empty containers 34 entering the filling zone from an input side of the conveyor 32. The containers 34 are filled with liquid product while the beam 40, nozzles 38 and containers 34 continue to move synchronously along with the conveyor 32. Upon completion of the filling, the nozzles 38 are retracted from the containers 34 and the beam 40 is stopped and reversed. The beam moves at a very rapid speed back toward the input side of the conveyor and stops at its initiation point.
Rotary filling systems and in-line filling systems have several advantages and disadvantages as compared to the other. As stated above, rotary filling machines are the fastest configuration because they allow for rapid, continuous motion of containers without the need for reversing or shifting the movement of any system components. In order to increase the throughput of a rotary filling machine, for a given rate of rotation of the rotor 42, the number of filling stations is increased. However, this may require increasing the diameter of the rotor. It is generally faster and easier to make a product changeover of an in-line machine from one product type or container type to another. It is also easier, on average, to increase the number of filling stations to an in-line system simply by adding modules to the system. Walking beam filling systems are described in detail in U.S. Pat. No. 5,878,796 and U.S. Pat. No. 6,761,191, the disclosures of which are hereby incorporated by reference herein in their entireties.
Each of the liquid filling systems requires one or more valves in the system to precisely dispense the desired amount of liquid product into the containers being filled. The valves are typically controlled by synchronized cams, hydraulic cylinders or air cylinders. Various types of valves have been used in automated liquid filling machines. For example, U.S. Pat. No. 5,058,632 describes a filling valve assembly specifically designed for use in bottling carbonated liquids, the disclosure of which is hereby incorporated by reference herein in its entirety. The filling valve described therein comprises a housing with a chamber therein. The chamber has an inlet opening for receiving liquid product into the chamber. A portion of the chamber defines a valve seat. A cylindrical valve stem extends through the chamber of the housing and out of the chamber through an opening in the valve seat. The valve stem has valve seal located within the chamber. Movement of the valve stem moves the valve seal moves between a closed position in which the valve seal is seated firmly on the valve seat and an open position in which the valve seal is moved away from the valve seat thereby creating a flow path between the valve seal and the opening in the valve seat. The opening in the valve seal is in fluid communication with the outlet of the valve. The valve may be actuated by a cam or a lever which are operably coupled to the valve stem to move the valve stem between the open and closed positions.
Another valve is disclosed in U.S. Pat. No. 6,761,191. The valve is quite similar to the valve described immediately above, except that it provides for almost complete product displacement (the condition in which the valve seats at the final point of discharge through the outlet) and it is actuated using pneumatic pressure and air cylinders.
These valves have various drawbacks when used for filling containers with semi-viscous liquids and/or liquids having mixed-in solid particles or particulate. A significant drawback to each of the previously described valves is that the valves have areas prone to clogging and product entrapment. In addition, none of these valves provides for low velocity discharge prior to the product reaching the point of vertical dispensing. A low velocity discharge prior to vertical dispensing nas several important benefits including better control of product flow through the nozzle, reduction of spurting, scatter and foaming during the product dispensing and smoother product flow upon opening of the valve from the closed position. In addition, the valve disclosed in U.S. Pat. No. 5,058,632 will be susceptible to dripping because the valve seat does not seal at the final point of discharge through the outlet, sometimes referred to as complete or positive displacement of product.
Accordingly, there is a need for an improved valve for liquid filling systems which overcomes the deficiencies of previous valves.